Reverse seam can with hermetic drumhead



Dec. 19, 1967 R. L, JOOSTEN ETAL 3,358,876

REVERSE SEAM CAN WITH HERMETIC DRUMHEAD Filed Sept. 14. 1964 FIG FIG. 4 I

N2 v. w mwnr VJA T E W United States Patent 3,358,876 REVERSE SEAM CAN WITH HERMETIC DRUMHEAD Richard Leo Joosten, Cary, and Richard Conrad Thorp, Crystal Lake, Ill., assignors to American Can Company,

New York, N.Y., a corporation of New York Filed Sept. 14, 1964, Ser. No. 396,020

4 Claims. (Cl. 220-67) This invention relates to a container seam and a method of forming the seam. It has particular reference to a seam which tightly clamps an end closure along its peripheral edge, and a method of forming the same.

One of the few disadvantages of the conventional double-seam is that the unseamed portion of the end closure is provided with a countersink wall adjacent the doubleseam. This countersink wall allows the central unseamed portion of the end closure to panel or deflect when the end closure is subjected to pressure or vacuum. This condition necessitates employing an end closure with substantial thickness which will provide the necessary resistance against such paneling. The countersink wall also allows the end closure to buckle, i.e. a permanent deformation of the countersink wall. Theoretically, the best solution to the problem of end closure paneling and buckling is to seam the end closure while it is maintained in a fiat disposition.

A typical commercial seam for securing a flat end closure comprises an inwardly directed seam which clamps the end closure at a single peripheral location above an inwardly directed ledge. While the single peripheral clamping of the end closure is adequate when container pressures are approximately atmospheric, the single peripheral clamping is incapable of maintaining the edge closure against displacement when the interior of the container is under pressurized or vacuumized conditions. In consequence, the commercial application of flat end closures has heretofore been limited to packages which are maintained at atmospheric pressures.

To function under pressures and/or vacuums, the periphery of the flat end closure must be tightly clamped or secured to eliminate relative movement between the periphery of the flat end closure and the elements which clamp or secure the end closure periphery. When such relative movement is eliminated, the strength of the end closure is determined by the tensile strength of the end closure material rather than the rigidity of the end closure, as explained above in the discussion of the problems presented by the countersink wall of the conventional end closure. An example of such high-tensile strength material is polyvinyl chloride, which also allows the customer to view the contained product. Additionally, the employment of a flat end closure eliminates the countersink wall and, therefore, the buckling problem presented by permanent deformations of the countersink wall.

It is therefore an object of the present invention to provide a tight seam construction between an end closure and a container body.

Another object is to provide a tight seam construction, for securing an end closure, which can be formed in an economical manner.

A further object is to provide a seam which tightly clamps an end closure along the margin edge thereof.

An additional object is to provide a seam which maintains an end closure in a buckle resistant manner with reduced plate weights.

Still another object is to provide a seam construction which will resist buckling and paneling, even when thin end closures are employed under pressurized or vacuumized conditions.

Still a further object is to provide a seamed construction which will maintain an hermetic seal between an end closure and a container body.

Yet another object is to provide a method of forming a seam which will tightly secure an end closure.

Numerous other objects and advantages of the invention will be apparent as it is understood from the following description, which, taken in conjunction with the accompanying drawings, discloses a preferred embodiment thereof.

The above objects are accomplished by a reverse seam construction which clamps the end closure along two nonplanar peripheral surfaces to tightly secure the flat central portion of the end closure.

Referring to the drawings:

FIG. 1 shows a perspective view of a container embodying the invention; and

FIGS. 2 through 5 are enlarged fragmentary sectional views showing the sequence of steps in forming the instant end seam, FIG. 5 also showing the completed seam.

As a preferred or exemplary form of the instant invention, FIG. 1 illustrates a metallic tubular container having a metallic body generally designated 10 and a metallic end closure generally designated 12. The end closure 12 may instead be fabricated from any material having high tensile strength, such as polyvinyl chloride, which is preferred when the packaged product is to be inspected by the consumer prior to purchase.

The container body is formed by a body blank whose longitudinal margins meet in a side seam generally designated 14, and at the end of the container body opposite the end closure 12, after the container has been filled, a metallic closure is aflixed to the container body by a conventional doubleseam 16 or, if desired, the container body may be closed by a reverse seam of the type specifically disclosed hereinafter with reference to end closure 12. The container body 10 may have a crosssection of circular, rectangular or elliptical configuration.

The tubular can body 10 is provided with an inwardly directed ledge 20 as shown in FIG. 2. This ledge is formed by turning the tubular wall 10 inwardly at 22 to form a radially extending annular wall 24. Adjacent the inner end of the annular wall 24 the container body is turned outwardly to form an inwardly directed bead 26 and an inclined wall 28 which merges at its outer end with a curved annular channel into which suitable sea-ling compound 32 is placed. Above the curved annular surface 30, the container body is provided with a tubular wall 33 which merges with an annular arcuate surface 35 located at the extremity of the container body.

The end closure 12 includes a central disc-like portion 11 and an integral peripheral vertical flange 31 which contacts the inside surface of the tubular wall 33 and maintains the end closure in position until the seaming operation is partially completed. The central disc-like portion 11 is placed over the inclined wall 28 and the sealing compound 32.

In the completed scam the tubular wall is turned downwardly and inwardly to form a curl 36 which clamps the flat central portion 11 and the tubular vertical flange 31. The flat central portion 11 is clamped by the curl 36 and the inwardly directed bead 20 and the peripheral flange 31 is clamped between an arcuate wall 38 and the curl 36 as shown in FIG. 5. Between the two clamped positions the curl 36 forces the end closure against the sealing compound 32 to improve the sealing effect as will be more fully explained hereinafter.

To effect the instant seaming method, a die 60 is located above the container and moved against the arcuate surface 35 to bend the upper extremity of the tubular wall 32 downwardly and outwardly as shown in FIG. 3. While the die 60 is preferred, other seam forming apparatus such as rollers may be employed. The bending of the upper end of the tubular wall is effected by an annular channel 62 which contacts the upper surface of the curl 36 and causes the leading edge of the curl to contact the closure member 12 along an annular surface 37 in the manner illustrated in FIG. 4. Continued downward movement of the die forces the surface 37 to move radially outwardly along the end closure 12. At this point, the inwardly extending ledge 22 is flexed downwardly to effect a first clamping action of the end closure 12 between the curl 36 and the wall 28. The wall 28 is flexed to a generally horizontal position as shown in FIGS. 4 and 5 and due to its tendency to return to the unflexed position the central portion 11 of the end closure is maintained tightly clamped between the curl 36 and the wall 28 of the ledge.

In the completed seam construction the periphery of the curl is curved to form an annular arcuate wall 38 as shown in FIG. 5. When the die 60 is moved to its lowermost position, the vertical flange 31 of the end closure 12 is clamped between the annular arcuate wall 38 and an abruptly curved surface 46 formed by the curl 36. As the curl 36 is moved from the position illustrated in FIG. 4 to the position illustrated in FIG. 5, the lower surface of the end closure 12 is pressed into sealing engagement with the compound 32. During this movement the leading end of the curl 36 is turned upwardly, causing the abruptly curved surface 46 to contribute a large clamping force.

The above described methodof forming a seam insures a tight connection between the tubular body and the end closure by clamping the end closure along two annular surfaces. Such clamping is a critical feature of the instant seam construction. Effective clamping of the end closure 12 is made possible by the elasticity of the container body. The inwardly directed ledge is flexed downwardly during the formation of the curl 36. The tendency of the ledge to return to its original position (FIG. 2), however, causes the end closure to be clamped between the curl 36 and the ledge 20. A second clamping is produced on the vertical flange 31 by the tendency of the curl 36 to return to its original or uncurled position. The abruptly curved surface 46 of the curl 36 insures a large clamping force along the vertical flange 31.

This clamping of the end closure allows the employment of thin end closures without any danger of buckling. The instant seam construction adds rigidity to the container body. Additional body rigidity is achieved by extending the curl 36 along the vertical flange 31. The tendency of the curl 36 to return to its previous uncurled condition provides a radial force which supports the container body via the vertical flange 31. This tendency also increases the rigidity and abuse resistance of the curl per se.

The instant seam construction maintains a hermetic seal for a variety of foods. Maximum sealing elfect of the compound 32 is realized because, during the seam formation, the compound is compressed and forced into sealing wardly 4 sequence the sealing compound is displaced both out between the verticalfiange31 of the closureand the arcuate wall 38 and inwardly along the inclined wall 28. This displacement of the sealing compound provides an elongated seal effectively preventing leakage of air or gas therethrough.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the steps of the method described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing its material advantages, the method and form hereinbefore described being merely a preferred embodiment thereof.

We claim:

1. A container comprising a container body, said body including an annular ledge adjacent to-. one end of said body and extending radially inwardly and axially upwardly, a tubular wall extending axially upwardly from and merging at its lower end with the outermost face of said ledge in alignment with the remainder of the container body, an annular channel between said ledge and said tubular wall, sealing compound within said channel, an annular curl connected with and extending upwardly and inwardly from the free end of said tubular wall, the free end of said curl projecting generally upwardly and radially outwardly, said container body being in combination with an end closure the peripheral portion of which extends between said ledge and the bottom of said curl and between the upper portion of said tubular wall and the free end of said curl, said ledge being flexed downwardly to urge said end closure upwardly against the bottom of said curl, said curl having a tendency to straighten so that said curl end urges said end closure against said tubular wall.

2. The container defined in claim 1 wherein said ledge comprises two layers, the uppermost of which is a downwardly and outwardly inclined wall, merging with said tubular wall at its lower portion the lowermost of said layers being an annular wall which merges with said conrelation with the end closure 12. During the seam forma- 7 tainer body.

3. The container defined in claim 2 wherein said upper and lower layers are joined at their radially inner ends by an inwardly directed head.

4. The container defined in claim 2 wherein said sealing compound extends between the location where said end closure is urged against said cylindrical wall and the location where said end closure is urged against said curl.

References Cited UNITED STATES PATENTS 636,646 11/1899 Draper 22067 X 1,364,640 1/ 1921 Plats 22067 2,100,480 11/1937 Hirshrnan 22067 X 2,251,987 8/1941 Conway 22067 X 2,744,217 5/1956 Aikman 22067 2,979,224 4/ 1961 Henchert 22067 3,128,008 4/ 1964 Henchert 229 -5.6 X

DONALD F. NORTON, Primary Examiner. JAMES R. GARRETT, Examiner. 

1. A CONTAINER COMPRISING A CONTAINER BODY, SAID BODY INCLUDING AN ANNULAR LEDGE ADJACENT TO ONE END OF SAID BODY AND EXTENDING RADIALLY INWARDLY AND AXIALLY UPWARDLY, A TUBULAR WALL EXTENDING AXIALLY UPWARDLY FROM AND MERGING AT ITS LOWER END WITH THE OUTERMOST FACE OF SAID LEDGE IN ALIGNMENT WITH THE REMAINDER OF THE CONTAINER BODY, AN ANNULAR CHANNEL BETWEEN SAID LEDGE AND SAID TUBULAR WALL, SEALING COMPOUND WITHIN SAID CHANNEL, AN ANNULAR CURL CONNECTED WITH AND EXTENDING UPWARDLY AND INWARDLY FROM THE FREE END OF SAID TUBULAR WALL, THE FREE END OF SAID CURL PROJECTING GENERALLY UPWARDLY AND RADIALLY OUTWARDLY, SAID CONTAINER BODY BEING IN COMBINATION WITH AN END CLOSURE THE PERIPHERAL PORTION OF WHICH EXTENDS BETWEEN SAID LEDGE AND THE BOTTOM OF SAID CURL AND BETWEEN THE UPPER PORTION OF SAID TUBULAR WALL AND THE FREE END OF 